Magnetically Isolated Phase Interior Permanent Magnet Electrical Rotating Machine

ABSTRACT

A magnetically isolated phase stator includes a stator phase section with two sides and a magnetically inactive isolation region on each side that prevents a permanent magnetic field from being shared from the stator phase section and another stator phase section of the stator. A magnetically isolated phase interior permanent magnet electrical rotating machine includes a magnetically isolated phase stator, a rotor, and an air gap between the stator and rotor defining a rotor-stator interface, the rotor having two or multiples of two permanent magnets arranged in parallel with opposing magnetic poles to direct magnetic flux through a pole of the rotor, through the air gap of the rotor-stator interface, and through a pole of the stator.

RELATED APPLICATIONS

This application takes priority to U.S. Application No. 61/431,779,filed Jan. 11, 2011, entitled Independent Phase Interior PermanentMagnet Generator, the entire contents of which are incorporated fullyherein by reference. U.S. Patent Application Publication No.2011/0089775, filed Oct. 19, 2010, entitled Parallel Magnetic CircuitMotor, is incorporated fully herein by reference.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

COMPACT DISK APPENDIX

Not Applicable.

BACKGROUND

In a conventional permanent magnet (PM) rotating machine having a rotorand stator, rotor magnets normally are mounted on the surface of therotor back iron and produce an air gap flux density equal to the area ofone of the permanent magnet's pole face area, as lowered by the air gapreluctance. Further, the magnets are located on the rotor in a mannerwhere two permanent magnets face into three stator poles to accommodatea conventional three-phase lap wound motor/alternator or generatordesign. Since the flux from the permanent magnets in this conventionaldesign is shared by three poles, the effect is diminished with regardsto increasing the gap flux density. Further, if one pole in such aconvention design is shorted, all three poles are shorted, which willcause the machine to lock. This does not provide for a fault tolerantdesign, and any imbalance on one of the phases will distort the otherphases.

With the rising cost of rare earth permanent magnet materials, rotatingmachine designers are looking for solutions that will reduce the amountof rare earth material used without sacrificing power density. Aconventional way of achieving this goal is to increase the number ofstator teeth that produce torque over the 360 degrees [2 pi radians]they occupy.

One such machine topology is a single phase permanent magnet synchronousmotor. A drawback with a single phase permanent magnet [PM] synchronousmotor/generator is that all of the rotor and stator teeth come into andout of alignment at the same time or angular intervals, producing theirminimum and maximum torque (motor) or power (generator) values at thesame time. Therefore, the average power (mechanical power/torque orelectrical power) is lower than the desired optimal torque or power.

A multiphase permanent magnet machine will produce a higher averagetorque or power since each phase will contribute to the torque or powerat different angular intervals. However, a distributed or lap woundpermanent magnet multiphase machine will have one or more stator teeththat do not produce torque or power over an angular interval since morethan one tooth forms a stator pole. This lowers the number of torque orpower producing teeth over 2 pi radians. In addition, the phases in apermanent magnet distributed or lap wound multiphase machine share thesame flux sources (i.e. the permanent magnets), which limits the amountof available energy stored in the magnetic field for a given phase sincethis energy is shared by all of the machine's phases. A concentratedwound multiphase machine increases the number of teeth producing torqueor power but does not address the problem with the phases sharing thesame flux source (i.e. the permanent magnets).

SUMMARY

A magnetically isolated phase stator has a stator phase section with twosides and an isolation region on each side that is magneticallyinactive. The stator phase section has two or more stator teeth definingstator poles, a winding slot between the stator teeth, and a phasewinding wound about each stator tooth.

Another magnetically isolated phase stator has two or more stator phasesections that are magnetically isolated from each other by at least oneisolation region. The isolation region is a magnetically inactive regionor area. Each stator phase section has two or more stator teeth definingstator poles with a winding slot between the stator teeth and a phasewinding wound about each stator tooth. The phase winding is aconcentrated winding in one aspect.

A magnetically isolated phase interior permanent magnet electricalrotating machine includes a magnetically isolated phase stator, a rotor,and an air gap between the stator and rotor defining a rotor-statorinterface. The rotor has two or multiples of two permanent magnetsarranged with opposing magnetic poles (e.g. a north pole of a magnetfacing a north pole of another magnet or a south pole of a magnet facinga south pole of another magnet), which is referred to herein as aparallel arrangement. The opposing magnetic poles of the permanentmagnets in the rotor direct magnetic flux through a pole of the rotor,through the air gap of the rotor-stator interface, and through a pole ofthe stator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of dimensions of a rectangular permanent magnet.

FIG. 2 is a diagram of magnets on a conventional rotor.

FIG. 3 is a diagram of a conventional rotor.

FIG. 4 is a diagram of magnets of a rotor in a parallel arrangement.

FIG. 5 is a diagram of a magnetically isolated phase interior permanentmagnet electrical rotating machine.

FIGS. 6-7 are diagrams of a magnetically isolated phase interiorpermanent magnet electrical rotating machine.

FIG. 8 is a diagram of an isolation region of the magnetically isolatedphase interior permanent magnet electrical rotating machine of FIG. 6-7.

FIG. 9 is a diagram of a magnetically isolated phase interior permanentmagnet electrical rotating machine.

FIG. 10 is a diagram of a magnetically isolated phase interior permanentmagnet electrical rotating machine.

FIG. 11 is a diagram of a magnetically isolated phase interior permanentmagnet electrical rotating machine with arc segments.

FIG. 12 is a diagram of a magnetically isolated phase interior permanentmagnet electrical rotating machine.

FIG. 13 is a diagram depicting a rotor without a bridge.

FIGS. 14-15 are diagrams of a saturatable bridge in a rotor.

FIG. 16 is a wiring diagram for a magnetically isolated phase interiorpermanent magnet machine.

FIG. 17 is a diagram of magnetic polarity in a magnetically isolatedphase interior permanent magnet electrical rotating machine.

FIGS. 18-19 are diagrams of creating one or more isolation regions in amagnetically isolated phase interior permanent magnet electricalrotating machine.

FIGS. 20-21 are diagrams of creating one or more isolation regions in amagnetically isolated phase interior permanent magnet electricalrotating machine.

FIGS. 22-23 are diagrams of creating one or more isolation regions in amagnetically isolated phase interior permanent magnet electricalrotating machine.

FIG. 24 is a diagram of a mirrored magnetically isolated phase interiorpermanent magnet electrical rotating machine.

FIG. 25 is a diagram of a mirrored magnetically isolated phase interiorpermanent magnet electrical rotating machine.

FIG. 26 is a diagram of a mirrored magnetically isolated phase interiorpermanent magnet electrical rotating machine.

FIGS. 27-30 are diagrams of a generator operation.

FIGS. 31-32 are graphs of voltage in a generator operation.

FIG. 33 is a diagram of a tip modified stator pole of a stator in amagnetically isolated phase interior permanent magnet electricalrotating machine.

FIGS. 34-37 are diagrams of a motoring operation.

FIGS. 38-40 depict a rotor with an arch bridge connecting rotor polesections between the permanent magnets.

DETAILED DESCRIPTION

A magnetically isolated phase stator of the present disclosure has twoor more stator phase sections (also referred to as sectors) that aremagnetically isolated from each other by at least one isolation region.An isolation region is a magnetically inactive region or area, such asone or more apertures and/or one or more areas with magneticallyinactive material. Each stator phase section has two or more statorteeth defining stator poles with a winding slot between the stator teethand a concentrated phase winding wound about each stator tooth.

A magnetically isolated phase interior permanent magnet electricalrotating machine (MIP-IPM-ERM) includes the above-described stator, arotor, and an air gap between the stator and rotor defining arotor-stator interface. The rotor has two or multiples of two permanentmagnets arranged with opposing magnetic poles (e.g. a north pole of amagnet facing a north pole of another magnet or a south pole of a magnetfacing a south pole of another magnet), which is referred to herein as aparallel arrangement. The opposing magnetic fields of the permanentmagnets in the rotor direct magnetic flux through a pole of the rotor,through the air gap of the rotor-stator interface, and through a pole ofthe stator. The machine may be configured, for example, as a motor or agenerator. A motor may be configured, for example, as a hub motor orother motor. In another example, the machine is a wind generator or windturbine.

The MIP-IPM-ERM has the highest rotor to stator active area (a ratio ofstator poles to rotor poles) for a multiphase permanent magnet machine,which is very desirable. The rotor to stator active area of this machineapproaches that of a single phase permanent magnet synchronous rotatingmachine and equally addresses the problems with the phases sharing thesame flux source by magnetically isolating each of the phases. That is,if one pole of a phase section or an entire phase section is shorted,the other phase sections are not shorted and will continue to operate.This provides a fault tolerant design. Moreover, any imbalance in one ofthe phase sections will not distort the other phase sections. Whencompared to a conventional interior permanent magnet machine, theMIP-IPM-ERM uses fifty-percent less rare earth permanent magnet materialwith a thirty-percent increase in power density, where both machineshave the same exterior dimensions or volume.

FIG. 1 depicts dimensions of a rectangular permanent magnet, whichinclude its length (L_(M)), width (W_(M)), and depth (D_(M)). Equation 1illustrates a hyperbolic function that relates the flux density producedby a permanent magnet to the permanent magnet's dimensions illustratedin FIG. 1.

$\begin{matrix}{B_{\min} = \frac{\begin{matrix}{\left( \frac{B_{r}}{\pi} \right) \cdot} \\\begin{bmatrix}{{{atan}\left\lbrack \frac{{Wm} \cdot {Dm}}{{\left( {2 \cdot Z} \right) \cdot \sqrt{{Wm}^{2} + {Dm}^{2} + {4 \cdot}}}Z^{2}} \right\rbrack} - {atan}} \\\left\lbrack \frac{{Wm} \cdot {Dm}}{2 \cdot \left( {Z + {Lm}} \right) \cdot \sqrt{{Wm}^{2} + {Dm}^{2} + {4 \cdot \left( {z + {Lm}} \right)^{2}}}} \right\rbrack\end{bmatrix}\end{matrix}}{10000}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

The flux density (B) of a permanent magnet is governed by its pole facearea, and the length between the poles produces the field intensity (H).The maximum flux density for a permanent magnet outside of a magneticcircuit is approximately equal to one-half the residual flux density(Br), and the maximum flux density for a permanent magnet in a circuitwould be a circuit without an air gap where the flux density would beequal to Br. However, a permanent magnet that is in a circuit without anair gap has a field intensity close to zero. When a permanent magnet isused in a rotating machine, the flux density in the air gap provides theworking field. Due to the reluctance in the air gap, the value of thisflux density is between one-half and three-fourths of the Br.

As shown in FIG. 2, the rotor 202 of some conventional motors hasinterior permanent magnets 204. However, the rotor magnets generally aremounted on the surface 206 of the rotor back iron 208 and produce an airgap flux density equal to the area of one of the permanent magnet's poleface area, as lowered by the air gap reluctance. Thus, the flux islimited by the pole face area of one permanent magnet 210 having a poleface length of L0 inches. Using a high grade neodymium permanent magnet,the air gap flux density is about 0.8 Tesla.

In addition, as shown in FIG. 3, the magnets are oriented in a mannerwhere two permanent magnets face into three stator poles to accommodatea conventional three-phase lap wound design. Since the flux from thepermanent magnets in this conventional design is shared by three poles,the effect is diminished with regards to increasing the gap fluxdensity. Further, if one pole in such a convention design is shorted,all three poles are shorted, which could cause the machine to lock ifthe short was significant. This does not provide for a fault tolerantdesign. Any imbalance on one of the phases will distort the otherphases.

The machine of the present disclosure overcomes limitations ofdiminished air gap flux density due to limitations of the permanentmagnets pole face area. It also provides fault tolerance because one ormore phases may operate when a phase or multiple phases becomeinoperable. Moreover, it provides phase balancing so that one phase willnot distort another phase.

FIG. 4 depicts a portion of a rotor 402 of a MIP-IPM-ERM of the presentdisclosure having permanent magnets 404 mounted on the interior 406 ofthe rotor back iron 408. The flux from two permanent magnets 410 and 412arranged in parallel combine to produce a flux density through a rotorpole 414 that is much greater than the flux produced through a rotorpole in a conventional permanent magnet (PM) rotating machine. In themachine of the present disclosure, the flux is produced by two permanentmagnet pole faces with lengths of L1 inches and L2 inches each facinginto a pole face that has a length of L3 inches. Thus, the two permanentmagnets produce a flux of (L1+L2)/L3 through the rotor pole 414.

When, for example, the pole face of the magnet 210 in FIG. 2 has alength L0 of 0.262 inches, the lengths L1 and L2 of the pole faces ofthe magnets 410 and 412 in FIG. 4 both are 0.375″, and the length L3 ofthe rotor pole 414 in FIG. 4 is 0.262″, a “virtual” permanent magnetresults in the rotor 402 of FIG. 4 that has a pole face area 2.86 timesgreater than a pole face area of a magnet 210 that could be mounted onthe surface 206 of the rotor back iron 208 shown in FIG. 2.

FIG. 5 depicts a portion of a magnetically isolated phase interiorpermanent magnet electrical rotating machine 502 having a rotor 504 anda stator 506. The rotor 504 has interior mounted permanent magnets 508arranged in parallel. The stator 506 has phase section A 510, phasesection B 512, and phase section C 514, each with coils 516 wrappedaround teeth 518.

Each of the stator's 506 phase sections 510-514 is isolated bymagnetically isolating areas 520-524, such as stator isolation regions.That is, a stator phase section is magnetically isolated from anotherstator phase section by a magnetically isolating area, such as a statorisolation region.

An isolation region is a magnetically inactive region or area, such asone or more apertures, one or more areas with magnetically inactivematerial, and/or one or more other magnetically inactive areas. Themagnetically inactive region prevents a permanent magnetic field frombeing shared between one stator phase section and another stator phasesection. Thus, a given stator phase section does not share the flux ofany rotor permanent magnet with another stator phase section. Thisprevents catastrophic third harmonic distortion if a stator phasesection becomes unbalanced. Moreover, if a fault occurs in one statorphase section, it can simply be removed from the circuit withoutaffecting the operation of the remaining stator phase sections,resulting in a fault tolerant machine. In the conventional lap woundmachine, if a phase is short circuited, even if the output of that phaseis removed from the circuit, the short in the faulted phase willcontinue to absorb energy from the air gap thereby reducing the amountof stored energy to the other phases and continuing to producedistortion in the remaining phases.

FIGS. 6-8 depicts an exemplary embodiment of a stator-rotor interface ofa magnetically isolated phase interior permanent magnet electricalrotating machine (MIP-IPM-ERM) 602. While the example of FIGS. 6-8depicts a three-phase machine (three electrical phases), two electricalphases, four electrical phases, or another number of electrical phasesmay be used. The machine can be, for example, a generator, a motor, oran alternator.

The machine 602 has a stator 604 and a rotor 606 with an air gap 607between the stator and rotor defining a stator-rotor interface. Thestator 604 and rotor 606 each rotate about an axis of rotation 608.

The stator 604 has two or more stator phase sections (also referred toas sectors) 610-620 that each are magnetically isolated from each otherby a magnetically isolating area, such as one or more stator isolationregions 622-632. That is, no stator phase section shares a permanentmagnet field with another phase. The electrical phases of the stator 604are evenly distributed. The phase sections also are evenly distributedover the stator 604 of FIG. 6. Alternately, the phase sections can beevenly distributed over half or another portion of the stator.

Phase windings 634 (also referred to as coils) are wound about statorteeth 636 (alternately referred to as stator poles 637) through phasewinding slots 638. For example, a phase winding slot 638 is an aperturein the stator core material 640 (stator back iron), and the stator mayhave two or multiples of two teeth. Magnetic flux is directed throughthe poles 636 of the stator.

In one example, the phase winding is a concentrated winding. However,the phase winding may not be a lap wound (distributed) winding, whichcould cause the machine to lock up or cause distortion when one phase isshorted to one or more other phases, as explained herein. Thus, thephase winding in this example is a concentrated, non-distributedwinding.

While six stator phase sections 610-620 and six stator isolation regions622-632 are depicted in the example of FIGS. 6-8, a different number oftwo or more stator phase sections and a different number of two or morestator isolation regions may be used in other examples.

The stator isolation regions 622-632 each may be arranged on or about arespective isolation region axis 642-652, such as at a selected distance(for example, angular or circumferential distance) from a reference 654.For example, a reference 654 may be designated as zero degrees on thestator 604 along the axis of rotation 608, and an isolation region axis642-652 may be defined as an angular distance 655 (see FIG. 7), such asa selected number of degrees, from the reference. An isolation regionaxis 642-652 also may be defined as an angular distance from anotherisolation region axis. Radians, degrees, or another measurement may beused.

In the example of FIGS. 6-8, the reference 654 is designated as zerodegrees (or radians), the angular distance to an isolation region axis642-652 is sixty degrees (or radian equivalent) from the reference, andeach other isolation region axis is defined at sixty degree (or radianequivalent) intervals from the reference, e.g. 60, 120, 180, 240, 300,and 360 (or 0). Other angular distances may be selected for othermachines. For example, in one embodiment of a 2-phase machine, theangular distance is selected to be 45 degrees (or radian equivalent)from a selected reference, and in an embodiment of a 4-phase machine,the distance is selected to be 22.5 degrees (or radian equivalent) froma selected reference. In another example, the angular distances betweentwo or more isolation region axes are not equal. For example, theangular distance from a reference to a first isolation region axis is afirst angular distance, and an angular distance from the first isolationregion axis to a second isolation region axis is a second angulardistance.

The selected reference may be any reference on or with respect to thestator. In the example of FIGS. 6-8, the reference 654 is along an axisextending from a center point 656 of the axis of rotation 608 of thestator 604 to the outer circumference 657 of the stator. Angulardistances for each isolation region axis 642-652 delineating each phasesection 610-620 are measured from that reference 654. Alternately, forexample, a first angular distance for a first phase section 612 ismeasured from the reference 654 to a first isolation region axis 642,and a second angular distance for a second phase section 610 is measuredfrom the first isolation region axis 642 to a second isolation regionaxis 652. Alternately, a stator is split into two or more sections, witheach section having two ends, and with each end having an isolationregion or a portion of an isolation region.

In FIG. 6, two opposing isolation region axis 642 and 648, 644 and 650,and 646 and 652 form an isolation region plane 656, 658, and 660,respectively, extending from one isolation region 622, 624, and 626 toan opposing isolation region 628, 630, and 632, respectively. Theisolation region planes 656, 658, and 660 divide the stator into the sixphase sections.

Each stator phase section 610-620 has one side defined by one isolationregion, and another side defined by another isolation region. Forexample, a first phase section 610 has one side 664 defined by oneisolation region 632, and another side 666 defined by another isolationregion 622. Alternately, the isolation region axes 634-644 define thesides of the sectors 610-620. For example, a first phase section 610 hasone side 664 defined by one isolation region axis 652, and another side666 defined by another isolation region axis 642.

Referring still to FIG. 6, half of an isolation region 622-632 isconfigured on each side of a corresponding isolation region axis 642-652in the stator 604. For example, a portion, such as half, of theisolation region 622 is configured on one side 668 of the isolationregion axis 652, and another portion, such as the other half, of theisolation region is configured on the other side 670 of the isolationregion axis.

The isolation region 622-632 may be defined as an offset angulardistance 672, such as an offset about an isolation region axis. WhileFIGS. 6-8 depict one half of the isolation region 622-632 configured oneach side of the isolation region planes 658-662 (and correspondingisolation region axes) on opposing sides of the stator 604, theisolation regions 622-632 may be configured on each side of thecorresponding isolation region axis 642-652 in the stator 604 and notstrictly along isolation region planes (and corresponding isolationregion axes).

In addition, the isolation region need not be split in half across anisolation region axis. A greater portion of the isolation region may beconfigured on one side of an isolation region axis and a lesser portionof the isolation region may be configured on the other side of theisolation region axis. Moreover, the length of two or more isolationregions along an isolation region axis may be the same or different (oneaxial length may be greater than another). Further, while the isolationregions 622-632 of FIGS. 6-8 are depicted as approximatelyfrusto-conical having an axial length 674 (along the axial dimension)and an offset angular distance 672 (angular dimension) defining an innerside 676, an outer side 678, one edge side 680, and an another edge side682 of the isolation region, an isolation region may have one or moreother shapes (rectangle/rectangular, circle/circular, oval/ovular,notch, non-uniform area, etc.), and the shape or shapes of one isolationregion may be different than the shape or shapes of another isolationregion. The total region encompassed by one isolation region may be thesame as or different than the total region encompassed by anotherisolation region.

One or more of the isolation regions 622-632 optionally may beconfigured with phase windings. As depicted in FIG. 7, the isolationregion is an aperture defined as an offset angular distance 672, withhalf of the offset on each side of an isolation region axis, and theisolation region is at equal intervals of a selected phase sectionangular distance 655 from a reference. A winding slot area 684-686 isconfigured on each side of the isolation region, with half of a windingslot depicted in FIG. 8 on each side of the isolation region. Windings687 may be wound in the winding slot areas 684-686, such as around teethadjacent the winding slot areas.

As depicted more clearly on FIG. 7, a pole arc 702 defines the positionof the winding slot, for example, by defining the distance between thewinding slots (and, therefore, the rotor teeth). For example, the polearc is an angular distance (in degrees or radians). The pole arc 702also defines the distance from one side of the isolation region to anadjacent winding slot. In the example of FIG. 7, the pole arc 702 is anangular distance (in degrees or radians) from one side 704 of theisolation region 622 to a center point or axis 706 of an adjacentwinding slot 708 or from the other side 710 of the isolation region 622to a center point or axis of an opposing adjacent winding slot (see FIG.6). The pole arc 702 in this example also is an angular distance (indegrees or radians) from the center point or axis 706 of the adjacentwinding slot 708 to the center point or axis 712 of a next adjacentwinding slot 714 (with no intervening isolation region). Thus, thedistance from an isolation region axis 642 of the isolation region 622to the center point or axis 706 of the adjacent winding slot 708 isone-half of the offset angular distance 672 plus one pole arc angulardistance 702.

Referring again to FIG. 6, the rotor 606 has two or more rotor segments688. Each rotor segment has two permanent magnets 690-692 mountedinterior to the rotor core 694 and configured in a parallel arrangementto transfer magnetic flux through a rotor pole 696. The parallelarrangement means a north magnetic pole of one magnet faces the northmagnetic pole of another magnet or a south magnetic pole of one magnetfaces the south magnetic pole of another magnet. Both parallel facingmagnetic poles, which are two poles of the same magnetic orientationfacing each other in parallel, point to one pole of the stator through apole of the rotor and the air gap.

A first rotor segment, for example, has a magnetic field from two rotorinterior permanent magnets configured in parallel. A second, adjacentrotor segment is configured with an opposite magnetic field than thefirst rotor segment. For example, a first rotor segment is configuredwith two north facing interior permanent magnets in parallel, and asecond, adjacent rotor segment is configured with two south facinginterior permanent magnets in parallel.

No stator phase section 610-620 shares a permanent magnet field withanother phase section. As a result, each phase section is magneticallyisolated from, and is independent of, each other phase section.Therefore, if one stator phase section becomes inoperable, each otherphase section still is operable. Thus, the machine 602 has redundancy.Moreover, such magnetic isolation eliminates the 3rd harmonic distortionand phase imbalance issues when the machine is configured as agenerator. When the machine is configured as a motor, it eliminates theproblem of the motor locking up when one electrical phase is shorted.

As described above, a phase section (alternately, sector) has two ormore poles. The total number of poles in the stator (and in a sector ofthe stator) is divisible by at least two or a multiple of two so thereare equal numbers of parallel facing magnetic fields (for example, northpole facing north pole or south pole facing south pole). In oneembodiment, the total number of poles in the stator is divisible byfour.

In the example of FIGS. 6-8, the pole arc is the number of degrees orradians from the center of one pole on the stator to the center of anadjacent pole on the stator with no intervening isolation region.Similarly, when aperture spacing between two adjacent poles is equal,the pole arc also will be the number of degrees from the center of onepole aperture in the stator to the center of an adjacent pole aperturein the stator with no intervening isolation region.

The methods discussed in connection with FIG. 6 may be used to createone or more isolation regions for stators having a different number ofelectrical phases and a different number of phase sections than shown inFIG. 6. For example, isolation regions may be created for two-phase,four-phase, or other phase machines and/or two, four, eight, and otherphase sections. Moreover, one or more isolation regions may be createdon a rotor using the techniques described herein.

In one aspect, the highest rotor to stator active area is achieved byminimizing the area of each stator isolation region between twomagnetically isolated section phases (also referred to as sectors). Inthis aspect, the isolation region area occupies a least angulardistance, such as a least number of degrees.

The pole arc, in degrees, is determined by:

$\begin{matrix}{{{pole}\mspace{14mu} {{arc}\;\left\lbrack \deg \right\rbrack}} = \frac{\begin{matrix}{{degrees}\mspace{14mu} {per}\mspace{14mu} {magnetically}\mspace{14mu} {isolated}} \\{{phase}\mspace{14mu} {section}\mspace{14mu} ({sector})}\end{matrix}}{{{{no}.\mspace{14mu} {of}}\mspace{14mu} {poles}\mspace{14mu} {per}\mspace{14mu} {sector}} + \frac{1}{{{no}.\mspace{14mu} {of}}\mspace{14mu} {electical}\mspace{14mu} {phases}}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$

The sector (that is, the degrees in a sector) and the number of polesper sector are selectable variables. A reciprocal of the electricalphases is equal to one divided by the number of electrical phases.

A phase section (sector) is magnetically isolated from another phasesection by the isolation region. The isolation region is an area thatmagnetically isolates two phase sections of the stator from each other.In one example, the isolation region is an aperture. In another example,the isolation region is one or more apertures, such as one or morenotches. In another example, the isolation region is comprised ofnon-magnetic material.

It should be noted that a phase section is different than an electricalphase. The electrical phase is generally the number of electrical phasesin a machine, such as 2 phase, 3 phase, 4 phase, 8 phase, and otherphases.

The isolation region may be defined by an isolation region offset,angular distance, area, or other mechanism. In one example, an isolationregion offset is an offset (in degrees) added to an aperture between twopoles of the stator (e.g. winding slot), a starting and ending angulardistance from a pole, a starting and ending angular clockwise distance(in degrees) or counterclockwise distance (in degrees) from a selectedpoint on the stator (for example, from zero degrees, 45, degrees, 60degrees, 90 degrees, 120 degrees, etc. of a center point), an angulardistance offset from a reference, axis or plane (e.g. isolation regionaxis or plane or phase section axis described herein), or anotherdistance. In one example, the isolation region is defined by an aperturehaving an angular distance offset about (e.g. a portion on either side)an axis or plane. In another example, the isolation region is anaperture, and an axis or plane (e.g. isolation region axis or planedescribed herein) bisects the isolation region. In another example, theisolation region is defined by an aperture that is offset between a poleof one section and the pole of another section, and the total angulardistance of the aperture is equal to the winding slot plus the isolationregion offset.

When the isolation region offset is determined as an angular distance,such as from or about an isolation region axis or plane, a reference, ora phase section end (or a reference from a winding slot), the totalisolation region offset (per sector) is given (in degrees) by:

$\begin{matrix}{{{isolation}\mspace{14mu} {region}\mspace{14mu} {{offset}\;\left\lbrack \deg \right\rbrack}} = {{pole}\mspace{14mu} {{arc} \cdot \frac{1}{{{no}.\mspace{14mu} {of}}\mspace{14mu} {electical}\mspace{14mu} {phases}}}}} & {{Eq}.\mspace{14mu} 3}\end{matrix}$

In this example, at least approximately one-half of the isolation regionoffset effectively is provided to one side of the sector, and the otherapproximately one-half of the isolation region is provided to the otherside of the sector. The application of this can be considered to takeseveral forms. Since the isolation region magnetically isolates eachsection, half of each total isolation region effectively is assigned toeach sector.

The total number of stator poles is given by:

$\begin{matrix}{{{{no}.\mspace{14mu} {stator}}\mspace{14mu} {poles}} = {{\frac{360}{{degrees}\mspace{14mu} {per}\mspace{14mu} {sector}} \cdot {{no}.\mspace{14mu} {poles}}}\mspace{14mu} {per}\mspace{14mu} {sector}}} & {{Eq}.\mspace{14mu} 4}\end{matrix}$

To satisfy the rotor geometry, the pole arc results in a number that,when 360 is divided by the pole arc, is divisible by 2.

The rotor has two or more rotor poles. The total number of poles in therotor is divisible by at least two or a multiple of two so there areequal numbers of parallel facing magnetic poles (for example,north-north or south-south). The total number of rotor poles is givenby:

$\begin{matrix}\begin{matrix}{{{{no}.\mspace{14mu} {rotor}}\mspace{14mu} {poles}} = \frac{360}{{pole}\mspace{14mu} {arc}}} \\{= \frac{360}{\frac{{degrees}\mspace{14mu} {per}\mspace{14mu} {sector}}{{{{no}.\mspace{14mu} {of}}\mspace{14mu} {poles}} + \frac{1}{{{no}.\mspace{14mu} {of}}\mspace{14mu} {electical}\mspace{14mu} {phases}}}}}\end{matrix} & {{Eq}.\mspace{14mu} 5}\end{matrix}$

Equations 2-5 may be referred to as optimization formulas.

2 Phase Geometry Example.

In one aspect, a two-phase geometry is selected. In the two-phasegeometry, the sector (e.g. degrees in a sector, also referred to as aphase section) is equal to 360 divisible by multiples of 4, for example90, 45, 30, 22.5, 18, 15, or 12. In one example, the sector (e.g.degrees per sector) is selected to be 90 degrees and the number ofstator poles in a sector is selected to be equal to 12. Then, fromEquation 2, the pole arc is 7.2 degrees:

$\begin{matrix}{{{pole}\mspace{14mu} {{arc}\;\left\lbrack \deg \right\rbrack}} = {\frac{90}{12 + \frac{1}{2}} = {7.2\mspace{14mu} \deg}}} & {{Eq}.\mspace{14mu} 6}\end{matrix}$

Applying Equation 3, the isolation region offset is 3.6 degrees:

isolation region offset=7.2·½=3.6 deg  Eq. 7

And, the number of stator poles is equal to 48:

stator poles=360/90·12=48,  Eq. 8

And, the number of rotor poles is equal to 50:

$\begin{matrix}{{{{no}.\mspace{14mu} {rotor}}\mspace{14mu} {poles}} = {\frac{360}{7.2} = {\frac{360}{\frac{90}{12 + \frac{1}{2}}} = 50}}} & {{Eq}.\mspace{14mu} 9}\end{matrix}$

Other example solutions are identified by the following Table 1.

TABLE 1 Stator Teeth (total Sector [deg] Poles/Sector per Stator) RotorPoles 18 4 80 90 18 12 240 250 18 20 400 410 22.5 4 64 72 22.5 12 192200 30 12 144 150 45 4 32 36 45 12 96 100 90 4 16 18 90 12 48 50

FIG. 9 shows an example of a 2 phase machine constructed using theresults of the optimization formulas.

3 Phase Geometry Example.

In another aspect, a three-phase geometry is selected. In thethree-phase geometry, the sector (e.g. degrees in a sector, alsoreferred to as a phase section) is equal to 360 divisible by multiplesof 3, for example 120, 60, 30, or 15. In one example, the sector (e.g.degrees per sector) is selected to be 60 degrees, and the number ofstator poles in a sector is selected to be equal to 8. Then, fromEquation 2, the pole arc is 7.2 degrees:

$\begin{matrix}{{{pole}\mspace{14mu} {{arc}\;\left\lbrack \deg \right\rbrack}} = {\frac{60}{8 + \frac{1}{3}} = {7.2\mspace{14mu} \deg}}} & {{Eq}.\mspace{14mu} 10}\end{matrix}$

Applying Equation 3, the isolation region offset is 2.4 degrees:

isolationregionoffset=7.20·1/3=2.4 deg  Eq. 12

And, the number of stator poles is equal to 48:

stator poles=360/60·8=48,  Eq. 12

And, the number of rotor poles is equal to 50:

$\begin{matrix}{{{{no}.\mspace{14mu} {rotor}}\mspace{14mu} {poles}} = {\frac{360}{7.2} = {\frac{360}{\frac{60}{8 + \frac{1}{3}}} = 50}}} & {{Eq}.\mspace{14mu} 13}\end{matrix}$

Other example solutions are identified by the following Table 2.

TABLE 2 Stator Teeth (total Sector [deg] Poles/Sector per Stator) RotorPoles 30 8 96 100 60 8 48 50

FIG. 10 shows an example of a 3 phase machine constructed using theresults of the optimization formulas.

Referring now to FIGS. 11 and 12, magnetic phase isolation does notrequire phase sections (sectors) to be magnetically “connected.”Therefore, an isolation region may be created by forming a phase sectionwith one or more apertures, notches, or inwardly recessed areas.Alternately, material may be removed from an area adjacent one or moreother apertures to form an isolation region. These embodiments can beused to reduce the amount of magnetic core material used to form thestator.

Referring to FIG. 11, the phase sections (sectors) are independent phasesections separated at or by one or more isolation regions. As shown inthe machine 1102 of FIG. 11, phase sections 1-6 of the stator core 1104can be constructed as individual arc segments 1106-1116, respectively,as opposed to a continuous ring. The isolation regions 1118-1128 arecreated by forming recessed areas in each arc segment. For example, afirst phase section arc segment 1106 has recessed areas 1130-1134(including half of an offset, half of a first notch, and half of asecond notch, respectively), and a second phase section arc segment 1108has recessed areas 1136-1140 (including half of an offset, half of afirst notch, and half of a second notch, respectively). Each of the arcsegments 1106 ad 1108 also includes a half winding slot area 1142-1144.Together, the recessed areas 1130-1134 and 1136-1140 create an isolationregion having an isolation region offset, a first notch, and a secondnotch. Though, a phase section may have an isolation area with one ormore apertures, notches, and/or or inwardly recessed areas.

Each of the arc segments 1106-1116 may be secured to stator corematerial, to other arc segments in the same phase section, or to otherarc segments by a securing device 1146-1148. For example, stacks of arcsegment laminants may be stacked for each phase section and secured by apin, rivit, screw, t-lock, clamp, notches to mount the phase section, orother securing device that holds the circular arc of the phase sectionwithin or on a structure, such as the core material or back iron.Alternately, the arc segment is a single laminant secored to stator corematerial.

In the embodiment of FIG. 11, the electrical phase-phase section (e.g.sector) relationship is as follows: phase sections 1 (1106) and 4 (1112)form electrical phase 1, phase sections 2 (1108) and 5 (1114) formelectrical phase 2, and phase sections 3 (1110) and 6 (1116) formelectrical phase 3. While the isolation region of example of FIG. 11includes an isolation region offset and two notch areas in each arcsegment, one or more of the offset, one or more notch areas, and/or oneor more other recessed areas may be used.

Referring now to FIG. 12, core material may be removed from an areaadjacent one or more other apertures to form an isolation region.Magnetic isolation between the phase sections 1202-1212 of a stator 1214in a machine 1216 also can be achieved or enhanced by forming one ormore other apertures 1218-1228 at the isolation regions 1230-1240, suchas by removing core material 1242 from the stator core between the phasesections, e.g. at the isolation regions.

Referring to FIGS. 13-15, the rotor core 1302 of a machine 1304 can beindividual arc segments as opposed to a continuous ring. If the rotorcore 1302 is comprised of a single ring, the segments are connected toeach other with “saturatable” bridge sections 1402 (see FIG. 14) toprevent the rotor permanent magnets from being “shorted” within therotor core material. The goal is to place as much permanent magnet fluxacross the air gap 1306 between the rotor 1302 and stator 1308 as ispossible. As shown in FIG. 13, if “saturatable” bridges are not used,the flux 1310 from the permanent magnets 1312-1314 would simply traversethrough the rotor core iron 1316 rather than across the air gap 1306 andthrough the stator phase section core material, resulting in themagnet's flux being shorted in rotor core iron 1314.

As shown in FIG. 14, a portion of the rotor core iron is judiciouslyremoved about the permanent magnets creating air regions 1404-1406separating the north (N) and south (S) poles of a permanent magnet 1312.A small section of core iron creates the saturatable bridge 1402 thatremains to connect the rotor segments 1408-1410. A portion of thepermanent magnet (PM) flux 1412 traverses the saturatable bridges. Sincethe bridge sections have a small cross section, the bridge sectionssaturate and force the majority of the PM flux 1412 across the air gap1306 into the stator phase section (e.g. stator sector).

Referring to the enlarged view of a section 1502 of the rotor 1302 inFIG. 15, it can be seen that the saturating bridge 1402 is the smallestsection of rotor iron 1314 that allows flux 1504 to traverse from thenorth pole 1506 and south pole 1508 of a permanent magnet 1510. Theprotrusion 1512 added (or remaining) in the staturating bridge 1402serves to hold the permanent magnet 1510 in place and is a structuralcomponent as opposed to being a magnetically active component.

FIG. 16 depicts an exemplary embodiment of a wiring diagram for a 3phase magnetically isolated phase interior permanent magnet machine,with each of the electrical phases repeated twice. The diagram of FIG.16 shows series windings in a phase. Alternately, the windings could beconnected in parallel or in a combination of parallel and seriesconnections.

Rotor Permanent Magnet's Magnetic Polarity

Referring to an embodiment of FIG. 17, a number of degrees that theisolation region in the stator occupies is determined by a number ofselected electrical phases and the pole arc for poles within a phasesection. In the exemplary optimization formulas herein, the pole arc isdependent upon other variables. For instance, pole arcs can beidentified that have a large fraction or other fraction of a degree. Ifthe number of stator poles shown in the three phase embodiment of FIG.10 (equations 10-13) was increased from 8 poles (which is depicted inFIG. 17) to 12 poles, the equations would return a pole arc of4.864864864 . . . 864 degrees. It would be difficult to manufacture astator with pole arcs to that fraction of degree since the fractionalpart of the degrees would result in an accumulated error over 360degrees. Though, these pole arcs are not excluded from the scope of thisdisclosure since the otherwise accumulated error could be equallydistributed between the phases. These pole arcs would work to form anoperating machine using the methods taught herein. For example, for atwo-phase machine, the number of degrees that a magnetically isolatedregion would occupy between the phase sections is the pole arc dividedby two. For a three-phase machine, the number of degrees that amagnetically isolated region would occupy between the phase sections isthe pole arc divided by three. For a four-phase machine, the number ofdegrees that a magnetically isolated region would occupy between thephase sections is the pole arc divided by four, and so on. The number ofdegrees the isolation region occupies also determines both themechanical and electrical degrees offset between the phases.

FIGS. 18-19 depict another exemplary embodiment of creating one or moreisolation regions in a magnetically isolated two-phase interiorpermanent magnet electrical rotating machine. A stator section 1802 of asingle phase topology is depicted in FIG. 18. The stator section 1802 issplit into two stator segments 1804 and 1806, and the second statorsegment is rotated clockwise by a number of degrees equal to one-half ofthe pole arc. In the above example of FIG. 10, the pole arc is 7.2degrees. Staying with that example, the second segment 1806 is rotated3.6 degrees. The void 1808 in the stator core 1810 after the rotation ofthe second stator segment 1806 becomes the isolation region, and each ofthe stator segments become the machine phase sections. If the rotor 1812was rotated in a counter clockwise manner, an advance by a rotor toothof (a distance of) one stator tooth represents 180 electrical degreesfor the phase created by the first stator segment 1804. Since the secondstator segment 1806 rotated clockwise, and the rotor is rotating counterclockwise, the phase created by the second stator segment 1806 will“lead” the phase created by first stator segment 1904 by 90 electricaldegrees. The relationship between mechanical degrees versus electricaldegrees is given by:

pole  arc = 7.2  deg   and$\frac{180\mspace{14mu} \deg}{{pole}\mspace{14mu} {arc}} = {25\mspace{14mu} {\deg.}}$

Therefore each mechanical degree equals twenty-five electrical degrees,By rotating the second stator segment 1806 by 3.6 mechanical degrees,the shift in electrical degrees between the phases is 90 degrees asshown by:

25 deg·3.6=90 deg; therefore 180 deg−90 deg=90 deg.

FIGS. 20-21 depict another exemplary embodiment of creating one or moreisolation regions in a magnetically isolated three-phase interiorpermanent magnet electrical rotating machine. A stator section 2002 of asingle phase topology is depicted in FIG. 20. The stator segment 2002 issplit into three stator segments 2004-2008. The second and third statorsegments 2006-2008 are rotated clockwise by a number of degrees equal toone-third of the pole arc. In the above example where the pole arc is7.2 degrees, the second and third stator segments 2006-2008 are rotated2.4 degrees with respect to thr first stator segment 2004. Next, thethird stator segment 2008 is rotated 2.4 degrees with respect to thesecond stator segment 2006. The voids 2010-2012 in the stator core 2014after the rotation of the second and third stator segments 2006-2008become the isolation regions, and each of the stator segments 2004-2008become the machine's phase sections. As in the two-phase discussion, itwas determined that one mechanical degree equals 25 electrical degrees.Since the second stator segment 2006 was rotated clockwise 2.4 degreeswith respect to the first stator segment 2004, and the third statorsegment 2008 was rotated clockwise 2.4 degrees with respect to thesecond stator segment 2006, the following phase relationships result:

25 deg·2.4=60 deg; therefore 180 deg−60 deg=120 deg.

Each of the machine's phases then has a phase shift of 120 electricaldegrees between one another.

FIGS. 22-23 depict another exemplary embodiment of creating one or moreisolation regions in a magnetically isolated four-phase interiorpermanent magnet electrical rotating machine. A stator section 2202 of asingle phase topology is depicted in FIG. 22. The stator section 2202 issplit into four stator segments 2204-2210. The second, third, and fourthstator segments 2206-2210 are rotated clockwise by a number of degreesequal to one-fourth of the pole arc. In the example where the pole arcis 7.2 degrees, the second, third, and fourth stator segments 2206-2210are rotated 1.8 degrees with respect to the first stator segment 2204.Then, the third and fourth stator segments 2208-2210 are rotated 1.8degrees with respect to the second stator segment 2206, and the fourthstator segment 2210 is rotated 1.8 degrees with respect to the thirdstator segment 2208. The voids 2212-2216 in the stator core 2218 afterthe rotation of the second, third, and fourth stator segments 2206-2210become the isolation regions, and each of the stator segments 2204-2210become the machine's phase sections. As in the two-phase discussion, itwas determined that one mechanical degree equals 25 electrical degrees.Since second, third, and fourth stator segments 2206-2210 were rotatedclockwise 1.8 mechanical degrees with respect to one another, thefollowing phase relationships result:

25 deg·1.8=45 deg.

Each of the machine's phases then has a phase shift of 45 electricaldegrees between one another.

A motor with any number of desired electrical phases can be produced inthe magnetically isolated phase interior permanent magnet electricalrotating machine.

In the examples above, a magnetically isolated two-phase interiorpermanent magnet electrical rotating machine would have four statorsegments each spanning 90 degrees with 12 teeth per segment, amagnetically isolated three-phase interior permanent magnet electricalrotating machine would have six stator segments, each spanning 60degrees with 8 teeth per segment, and a magnetically isolated four-phaseinterior permanent magnet electrical rotating machine would have eightstator segments each spanning 45 degrees with 6 teeth per segment, allhaving a pole arc of 7.2 degrees. This would result in all threemachines having 48 stator teeth and 50 rotor teeth. However, othermachines having other numbers of stator segments/phase sections,electrical degrees for a segment/phase section, stator teeth, rotorteeth, pole arc, and offset may be created and used.

In a magnetically isolated phase interior permanent magnet electricalrotating machine, all of the stator teeth are producing torquesimultaneously and at different angular intervals, thereby producing atorque or power at the stator to rotor interface of 96% (48 statorteeth/50 rotor teeth) as opposed to 70% or less for most conventionalpermanent magnet rotating machines.

Referring to FIG. 24, another embodiment for a mirrored magneticallyisolated phase interior permanent magnet electrical rotating machine2402 is based upon distributing a desired number of phase sections over180 angular degrees and then “mirroring” the phase section layout overthe remaining 180 degrees.

The electrical phases in the stator are evenly distributed. In oneexample, one or more sets of two opposing isolation regions 2404 and2406 are larger than one or more sets of two other isolation regions2408-2414, including one or more sets of two opposing isolation regions(2408 and 2412; 2410 and 2414) or isolation regions that otherwisemagnetically isolate phase sections. However, the electrical phases areevenly distributed. For example, a machine is divided into an upper half2416 and a lower half 2418 along a dividing or mirroring axis 2420. Theopposing set of isolation regions 2404 and 2406 dividing the upper andlower halves 2416-2418 has a isolation region area that is larger thanthe isolation regions 2408-2414 in the upper and lower halves.

This method can be used to construct a magnetically isolated phaseinterior permanent magnet electrical rotating machine when theoptimization formulas do not return a desired result for a given numberof rotor poles, teeth per segment, or another of the design criterion.For example, in a three phase topology in which it may be desirable forthe rotor to have 30 poles, the optimization equations would return apole arc of 11.996800853105839 degrees and would require 4.668 teeth persegment. Therefore, a pole arc of 12 degrees (360/30) could be used. Itwould still be desirable to use the optimized angular offset(displacement) for the isolation region. In this case, 12 degrees isdivisible by 3 (e.g. the number of electrical phases). Therefore, theisolation region would equal 4 degrees. Three stator segments separatedby two isolation regions are evenly distributed over 180 degrees andthen mirrored over the remaining 180 degrees. This will result inisolation regions with a different angular displacement located at themirroring axis where the mirroring occurs.

Alternately, as depicted in FIG. 25, the three stator segments occupyingthe first 180 degrees could be separated by two isolated regionsequaling two-thirds of a pole arc without losing the 120 electricaldegrees of displacement between the three phases. This arrangement ismirrored to the remaining 180 degrees. The methods of FIGS. 24-25 toproduce a mirrored machine further reduce the cost of the rare earthmagnets, thereby resulting in low cost, low wattage motors. The mirroredmachine of FIGS. 24-25 is an alternative to the optimized machine ofFIGS. 6 and 10.

Referring to FIG. 26, as with an optimized isolated phase interiorpermanent magnet electrical rotating machine described above, the statorcore material 2602 in the isolation regions of the mirrored machine 2604could also be eliminated. In this example, stator arc segments 2606-2616are created for the phase sections as in the example of FIG. 11, thoughusing the mirrored machine approach with at least two opposing isolationregions 2618-2620 being larger than two or more other opposing isolationregions 2622-2628 or other isolation regions.

Generator Operation

Referring to FIGS. 27-31, in this example, a magnetically isolated phaseinterior permanent magnet electrical rotating machine is operating as agenerator. An angular section of a stator 2702 and a rotor 2704 is shownwith three stator phase sections 2706-2710 or segments (phase one 2706,phase two 2708, and phase three 2710) with two teeth per stator phasesection. This simplified approach is used for the ease of illustratingand explaining the principles of the generator operation and does notnecessarily represent a preferred embodiment.

The rotor's initial angular position is with the phase 1 rotor andstator teeth in alignment and is at both zero electrical and 0mechanical degrees (FIG. 27) and equally at zero on the axis of thevoltage output graphs of FIG. 31 (phase 1 mechanical angle) and FIG. 32(phase 1 electrical angle). In phase 2, the rotor poles are moving “out”of alignment by 2.4 mechanical degrees when phase 1 is at 0 mechanicaldegrees and is at −120 electrical degrees, as shown on the voltageoutput graphs of FIGS. 31-32. In phase 3, the rotor poles are moving“into” alignment by 4.8 mechanical degrees when phase 1 is at 0mechanical degrees and is at 120 electrical degrees, as shown on thevoltage output graphs of FIGS. 31-32.

The rotor is rotating counter-clockwise. At the point shown in FIG. 28,phase 1's stator and rotor teeth are moving out of alignment by 2.4mechanical degrees and is at 60 electrical degrees in the voltage graphsof FIGS. 31-32. Phase 3's rotor and stator poles come into alignment andare at 0 mechanical degrees and at 0 electrical degrees in the voltagegraphs of FIGS. 31-32. Phase 2 underwent a flux reversal as it passedthrough 3.6 mechanical degrees, and the next set of rotor teeth are nowcoming into alignment with its stator teeth and are at 4.8 mechanicaldegrees and at −60 electrical degrees, as shown on the voltage graphs ofFIGS. 31-32.

As the rotor continues rotating counter-clockwise, and at the pointshown in FIG. 29, Phase 1 underwent a flux reversal as it passed through3.6 mechanical degrees, and the next set of rotor teeth are now cominginto alignment with its stator teeth and are at 4.8 mechanical degreesand is at 120 electrical degrees in the voltage graphs of FIGS. 31-32.Phase 2's rotor and stator poles come into alignment and are at 0mechanical degrees and at 0 electrical degrees in the voltage graphs ofFIGS. 31-32. Phase 3 rotor and stator teeth are now moving out ofalignment by 2.4 mechanical degrees and are now at −60 electricaldegrees on the voltage graphs of FIGS. 31-32.

As the rotor continues rotating counter-clockwise, and at the pointshown in FIG. 30, all of the phases return the same mechanical degreesas shown in FIG. 27. Phase 1 is at 0 mechanical degrees, phase 2 is at2.4 mechanical degrees, and phase 3 is at 4.8 mechanical degrees. Thedifference between FIG. 27 and FIG. 30 is that the flux has reversedthrough all of the phase windings and the electrical degrees for each ofthe phases, which are phasel: 0 electrical degrees, phase 2: 120electrical degrees, and phase 3: −120 electrical degrees, as shown inthe voltage graphs of FIGS. 31-32.

The induced voltage in an isolated phase interior permanent magnetelectrical rotating machine operating as a generator follows Faraday'sLaw as with other generators.

$\begin{matrix}{E = {N \cdot \frac{\Phi}{t}}} & {{Eq}.\mspace{14mu} 18}\end{matrix}$

Where N=the number of turns, dΦ=the change in flux (webers), and dt=timeincrement over which the change in flux occurs. In rotating machines, dtis typically replaced with seconds/radian.

The output waveform for a generator using the isolated phase interiorpermanent magnet electrical rotating machine topology can be tailoredusing pole shaping. For instance if the output waveform resembles asquare wave, the poles may be shaped to more closely approximate a sinewave by removing material from the stator pole (tooth) tips to create atip modified (shaved/removed) stator pole (tooth) 3302, or alternatelythe rotor pole tips, as depicted in FIG. 33.

Motoring Operation

With reference now to FIGS. 34-37, an example isolated phase interiorpermanent magnet electrical rotating machine 3402 operates as a motor.An angular section of a stator 3404 and a rotor 3406 is shown with threestator phase sections 3408-3412 or segments (phase one 3408, phase two3410, and phase three 3412) with 2 teeth per stator phase section. Thissimplified approach is used for the ease of illustrating and explainingthe principles of motor operation and does not necessarily represent apreferred embodiment.

In FIG. 34, phase one's 3408 stator teeth are aligned with rotor teeth,phase two's 3410 stator teeth are offset by 2.4 degrees from the“leading” rotor teeth, and phase three 3412 is offset 2.4 degrees fromthe “trailing” rotor teeth, assuming a counter-clockwise rotating rotor3604. In this rotor position, the coils in the motor's phases (wound onthe teeth) are energized to produce the polarities shown. The forcesacting on the rotor 3406 at this position are due to the coils beingenergized and producing a magnetic flux that either repels or attracts arotor segment due to the flux from a permanent magnet traversing throughthe rotor segment. The flux produced by the phase 1 coil will berepelling the aligned rotor segments, the flux produced by the coils inphase 2 and phase 3 will repel the “leading” rotor segments and attractthe “trailing” rotor segments. The sum of the forces acting on the rotorwill rotate the rotor 3406 in a counter-clockwise direction.

As the rotor 3406 rotates in a counter-clockwise direction once therotor has moved an angular distance of 2.4 degrees, FIG. 35, the rotorpoles will move out of alignment with phase 1's rotor teeth, the rotorpoles will advance 2.4 degrees with respect to phase 2's stator teeth,and the rotor poles will move into alignment with phase 3's statorteeth. The current through the coils wound on phase 3's stator teeth isreversed, which in turn reverses the magnetic polarities on phase 3'srotor teeth to repel the aligned rotor teeth supporting rotor rotationin the counter-clockwise direction.

The rotor 3406 continues to rotate in a counter-clockwise direction.Once the rotor 3406 has advanced another 2.4 degrees, FIG. 36, the rotorpoles come into alignment on phase 2. The current through the coilswound on phase 2's stator is reversed, which in turn reverses themagnetic polarities on phase 2's rotor teeth to repel the aligned rotorteeth supporting rotor rotation in the counter-clockwise direction.

Once the rotor 3406 has advanced another 2.4 angular degrees, FIG. 37,the rotor poles move back into alignment with phase 1's stator teeth.The current through the coils wound on phase 1's stator teeth isreversed, which in turn reverses the magnetic polarities on phase 1'srotor teeth to repel the aligned rotor teeth supporting rotor rotationin the counter-clockwise direction.

This sequential switching of the coils wound on each of the phase'sstator teeth will continue rotating the rotor in a counter-clockwisedirection. Alternately, if the magnetic polarities were reversed on thephases 2 and 3 rotor teeth starting in the position shown in FIG. 34,the rotor would rotate in a clockwise direction. The sum of the magneticforces produced on the rotor by the current in the phase coils willappear as torque on the motor's output shaft. Some advancement orretarding of the switching angle of 2.4 degrees can be performed tooptimize performance due to the effects of inductances and backelectromotive forces.

In one embodiment, as depicted in FIGS. 38-40, the rotor has a bridgeconnecting rotor pole sections between the permanent magnets. The bridgein this embodiment is configured as or with an internal arch or otherarch. The arch eliminates a weak mechanical spot from rotor having anotch at the bridge connecting rotor pole sections between the permanentmagnets.

The arch eliminates the need to insert additional non-magneticlaminates, significantly reducing part count, cost, and manufacturingprocess requirements.

The arch reduces windage (and the accompanying noise) that is intrinsicto conventional rotor-stator interfaces by creating a smooth surface onthe rotor. This also reduces drag and increases efficiency. Sincewindage losses increase as a function of speed, the arch provides asignificant advantage during higher speed and variable speed operation.

The arch reduces cogging forces without the need for skewing thelaminations on either the rotor or the stator. This also reduces dragand increases efficiency.

Those skilled in the art will appreciate that variations from thespecific embodiments disclosed above are contemplated by the invention.The invention should not be restricted to the above embodiments, butshould be measured by the following claims.

1. A system comprising: a magnetically isolated phase stator comprising a stator phase section with two sides and a magnetically inactive isolation region on each side that prevents a permanent magnetic field from being shared from the stator phase section and another stator phase section.
 2. The system of claim 1 wherein the stator phase section has two or more stator teeth defining stator poles, a winding slot between the stator teeth, and a phase winding wound about each stator tooth.
 3. The system of claim 2 wherein the system comprises a magnetically isolated phase interior permanent magnet electrical rotating machine comprising the stator, a rotor, and an air gap between the stator and rotor defining a rotor-stator interface, the rotor comprising two or multiples of two permanent magnets arranged in parallel with opposing magnetic poles to direct magnetic flux through a pole of the rotor, through the air gap of the rotor-stator interface, and through a pole of the stator.
 4. A system comprising: a magnetically isolated phase stator comprising at least two magnetically isolated stator phase sections that are magnetically isolated from each other by at least one magnetically inactive isolation region, the at least one magnetically inactive isolation region preventing a permanent magnetic field from being shared between the magnetically isolated stator phase sections.
 5. The system of claim 4 wherein the stator phase section has two or more stator teeth defining stator poles, a winding slot between the stator teeth, and a phase winding wound about each stator tooth.
 6. The system of claim 5 wherein the system comprises a magnetically isolated phase interior permanent magnet electrical rotating machine comprising the stator, a rotor, and an air gap between the stator and rotor defining a rotor-stator interface, the rotor comprising two or multiples of two permanent magnets arranged in parallel with opposing magnetic poles to direct magnetic flux through a pole of the rotor, through the air gap of the rotor-stator interface, and through a pole of the stator. 